1. Field of Invention
The present invention relates to a projector which includes an electrooptic device for forming an optical image according to image information, a projection lens for enlarging and projecting the image formed by the electrooptic device, and an outer casing for covering the main body including the electrooptic device.
2. Description of Related Art
Hitherto, a projector has been known which includes a light source unit having a light source, an electrooptic device for modulating light emitted from the light source to form an optical image according to image information, a projection lens for enlarging and projecting the image formed by the electrooptic device, and an outer casing for accommodating these components.
Such projectors have been widely used for multimedia presentations at conferences, academic meetings, exhibitions, and the like.
In this case, in order to sharpen the image projected by the projector, an increase in brightness of the light source lamp as a light source is facilitated.
In such a projector in which an increase in brightness of the light source lamp is facilitated, it is necessary to increase power source capacity supplied to the projector, and electric power consumption inside the projector is increased therewith.
When the brightness of the light source is increased or the electric poser consumption is increased, the heating value increases therewith, whereby the temperature inside the projector increases, and in particular, operation of the electrooptic device, which is easily affected by heat, becomes unstable due to the heat inside the projector.
For this reason, an air inlet is formed in the lower surface of the outer casing, and external air is introduced as cooling air by a cooling fan from the air inlet to cool the electrooptic device.
On the other hand, while the projector is sometimes kept installed in a conference room, or the like, for a presentation, it is sometimes brought in as necessary, or is stored in another place after use. Therefore, the projector may preferably be reduced in weight and size in order to facilitate transportation.
However, even if cooling air is introduced by the cooling fan from the air inlet formed in the lower surface of the outer casing, the cooling air is blown spirally on the electrooptic device, so that the electrooptic device is not cooled uniformly. Therefore, uniform and efficient cooling of the electrooptic device is difficult.
In addition, spiral cooling air tends to spread toward the outside of the spiral, it is difficult to guide all the cooling air toward the electrooptic device, and cooling efficiency of the electrooptic device is decreased.
Therefore, according to the above-described conventional projector, cooling efficiency is decreased, and the device is insufficient to achieve an increase in brightness of the light source and a reduction in size of the projector.
The invention provides a projector including a cooling structure which efficiently cools the electrooptic device, and which can cope with an increase in brightness of the light source and a reduction in size of the device.
A projector according to the present invention may include an electrooptic device for forming an optical image according to image information, a projection lens for enlarging and projecting the image formed by the electrooptic device, and an outer casing for covering the main body including the electrooptic device. An air inlet takes in external cooling air is formed in the outer casing. The projector may also include a cooling fan for introducing cooling air from the air inlet to cool the electrooptic device, and a regulating fan opposing the cooling fan across the electrooptic device and for regulating the cooling air introduced by the cooling fan.
According to the present invention as described above, by opposingly disposing the cooling fan and the regulating fan, the flow of the cooling air introduced by the cooling fan can be formed in a substantially uniform linear flow. For this reason, if the electrooptic device is disposed between the cooling fan and the regulating fan, it is possible to blow substantially uniform linear cooling air on the electrooptic device.
This allows the electrooptic device to be uniformly and efficiently cooled without cooling only parts of the electrooptic device, and a cooling structure can be obtained which can cope with an increase in brightness of the light source and a reduction in size of the device.
In addition, the spirally diffused cooling air that has been exhausted from the cooling fan is allowed to flow by the regulating fan so as to converge. Therefore, it is possible to increase cooling efficiency of the electrooptic device, and in this respect, a cooling structure can be obtained which can cope with an increase in brightness of the light source and a reduction in size of the device.
In the projector as described above, the cooling fan and the regulating fan may be desirably constructed so that the blast volume thereof can be varied.
Here, in order to vary the blast volume of the cooling fan and the regulating fan, the number of rotations of the fans may be controlled by, for example, changing the size of the diameter of the fans, or by changing the magnitude of voltage supplied to the fans.
If the blast volume of the cooling fan and the regulating fan is variable as described above, it is possible to set the flow of air near the electrooptic device to an optimum flow in cooling the electrooptic device. This can further increase the cooling efficiency of the electrooptic device.
Furthermore, the blast volume of the cooling fan may preferably be larger than the blast volume of the regulating fan.
Here, since the regulating fan mainly regulates the flow of the cooling air introduced by the cooling fan, the blast volume of the regulating fan may be such a degree that a directional property is imparted to the cooling air.
Therefore, even if the blast volume of the regulating fan is reduced to be less than the blast volume of the cooling fan, the electrooptic device can be sufficiently and efficiently cooled when the above-described blast volume can be obtained. Moreover, since the voltage supplied to the regulating fan may be low in proportion to the blast volume of the regulating fan, it is possible to further decrease electric power consumption inside the projector, to reduce the heating value inside the projector, and to increase the cooling efficiency of the electrooptic device.
In addition, the above-described projector may desirably include a housing for optical components for accommodating optical components, such as lenses and mirrors, and the regulating fan may desirably be fixed to the housing for optical components.
If the regulating fan is fixed to the housing for optical components as described above, it is not necessary to newly provide a pedestal for fixing the regulating fan or to fix the regulating fan to the inner surface of the outer casing, and the regulating fan can be easily fixed without complicating the structure of the inside of the projector. This can facilitate manufacturing of the projector.
Furthermore, the regulating fan may preferably be provided with a filter for covering the regulating fan, the filter may preferably include a filter member having dust blocking properties, and a filter frame provided along the periphery of the filter member, and the filter frame may preferably be fixed to the housing for optical components.
If the regulating fan is fixed to the housing for optical components as described above, the entry of dust or the like into the electrooptic device can be prevented. Moreover, by covering the periphery of the electrooptic device by, for example, the housing for accommodating optical components, such as lenses and mirrors, and by disposing the regulating fan provided with the filter above the electrooptic device, the overall electrooptic device can be covered by the filter and the housing for optical components.
This can securely prevent the entry of dust or the like into the electrooptic device, and deterioration of the projected image due to adhesion of dust, or the like, to the electrooptic device can be prevented.
In addition, a temperature detection device for detecting the temperature of cooling air near the electrooptic device may desirably be provided between the cooling fan and the regulating fan, and the cooling fan and the regulating fan may desirably be controlled by the temperature detected by the temperature detection device.
Here, the temperature detection device may preferably be constructed so as to output a detection signal to a control substrate for controlling the cooling fan and the regulating fan.
If the temperature detection device is constructed as described above, for example, when it is detected that the temperature of the electrooptic device is high, the electrooptic device can be controlled so as to be rapidly cooled by increasing the number of rotations of the cooling fan and the regulating fan. Conversely, when it is detected that the temperature of the electrooptic device is low, the electrooptic device can be controlled so as to be slowly cooled by decreasing the number of rotations of the cooling fan and the regulating fan.
Incidentally, the reference temperature with respect to a high or low detected temperature is suitably determined on the basis of experimental results, or the like.
This allows the rotation of the fans to be easily controlled according to the elevation in temperature of the electrooptic device, so that the cooling efficiency of the electrooptic device can be easily optimized.
Furthermore, the regulating fan may preferably be dismountably provided. If the regulating fan is dismountably provided as described above, the components can be shared with a projector in which the brightness of the light source lamp is not increased, in other words, the brightness of the light source lamp is low, and the regulating fan is not required.